Influence of solvent on the electronic structure and the photochemistry of nitrophenols
Influence of solvent on the electronic structure and the photochemistry of nitrophenols
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溶剂对硝基酚电子结构和光化学的影响
DOI：
10.1039/d2ea00144f
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发表时间：
2023
期刊：
影响因子：
--
通讯作者：
Nizkorodov, Sergey A.
中科院分区：
文献类型：
--
作者：
Dalton, Avery B.;Le, Scott M.;Karimova, Natalia V.;Gerber, R. Benny;Nizkorodov, Sergey A.
以前的研究表明，硝基芳烃在有机溶剂中的光化学反应与在水溶液中的光化学反应有很大的不同。本文比较了2-硝基苯酚（2NP）、4-硝基苯酚（4 NP）、2，4-二硝基苯酚（24 DNP）和2，4，6-三硝基苯酚（246 TNP）在2-丙醇和水中的光降解，以更好地了解硝基苯酚在大气有机颗粒物和水滴中的光化学损失。多色量子产率测定通过监测与UV/维斯光光谱在酸（未解离的硝基酚）或碱（硝基酚盐）的存在下，每个硝基酚的吸光度的损失。在有机相和水相中的损失率之间没有有序变化：2NP和4 NP在两种溶剂中具有相似的产率。246 TNP是这些结果中的异常值，因为其在酸化的2-丙醇和水中均解离，这是由于其异常强的酸性。值得注意的结果是，与在水中相比，仅对于24 DNP，在2-丙醇中发现的反应性显著增加。采用含时密度泛函理论计算方法，采用类导体极化连续模型或少量溶剂分子的显式溶剂化作用，对体系的激发态能量和吸收光谱进行了表征.显式溶剂计算表明，24 DNP在2-丙醇中的反应性增强是由于2-丙醇分子和激发态的-NO2基团之间的强相互作用。对于其他硝基酚，溶剂对电子结构的影响是最小的。总的来说，在这项工作中的观察表明，溶剂对硝基酚的电子结构和凝聚相光化学的影响是最小的，除了24 DNP。
Previous studies have suggested that the photochemistry of nitroaromatics in organic solvents can vary significantly from the photochemistry in aqueous solutions. This work compares the photodegradation of 2-nitrophenol (2NP), 4-nitrophenol (4NP), 2,4-dinitrophenol (24DNP), and 2,4,6-trinitrophenol (246TNP) in 2-propanol and water to better understand the photochemical loss of nitrophenols in atmospheric organic particles and aqueous droplets. Polychromatic quantum yields were determined by monitoring the loss of absorbance of each nitrophenol with UV/vis spectroscopy in the presence of an acid (undissociated nitrophenol) or base (nitrophenolate). There was no orderly variation between loss rates in the organic and aqueous phases: 2NP and 4NP had similar yields in the two solvents. 246TNP was an outlier in these results as it dissociated in both acidified 2-propanol and water due to its exceptionally strong acidity. A notable result is that only for 24DNP was a dramatically increased reactivity found in 2-propanol compared to that in water. Time-dependent density functional theory calculations were carried out to characterize the excited state energies and absorption spectra with a conductor-like polarizable continuum model or explicit solvation by a few solvent molecules. Explicit solvent calculations suggest the enhanced reactivity of 24DNP in 2-propanol is due to the strong interaction between a 2-propanol molecule and an –NO2 group in the excited state. For the other nitrophenols, the solvent effects on electronic structure were minimal. Overall, the observations in this work suggest that solvent effects on the electronic structure and condensed-phase photochemistry of nitrophenols are minimal, with the exception of 24DNP.